Slide 11:

Workbench :

Workbench Machine: Pentium4 “Northwood” 2.53-2.66 GHz. with Hyper-Threading
Operating System: Linux 2.4.18-SMP kernel. OS views each thread as a processor
BIOS setting to turn HT On/Off
PERL script to fork processes at the same time
“top” (Linux utility) to monitor processes (processor and memory utilization)
“time” utility to get timing statistics for each program
Ran each experiment 10 times and took the average execution time

Experiments: Single thread performance :

Experiments: Single thread performance Hyper-Threading does not degrade single thread performance

Experiments (Contd.) :

Experiments (Contd.) Contention for single FP unit increases execution time
Contention for data cache can lead to thrashing

Experiments (Contd.) :

Experiments (Contd.) Integer workloads perform well – 3 integer units
(2 double speed) are well utilized
Workloads with complementary resource requirements
perform well (intflt, memint)
OS plays important role when number of programs > number
of hardware contexts available

Experiments (Contd.) :

Experiments (Contd.)

Experiments (contd.) :

Experiments (contd.) Execution time with 3 kernel workload is less than that for 2!
Scheduling important!
intfltflt - int kernel has 100% of 1 thread, 50:50 between flt
and flt
fltfltint - flt kernel has 100% of 1 thread, 50:50 between int
and flt. Has higher execution time!

Project Goal :

Model Hyper-Threading on a simulator. Vary key parameters and study first order effects Project Goal